Outline

Objective

Aqueous humor reflects the microenvironment of the anterior chamber, and displays attributes that correlate with the immune privileged nature of this site. We wished to determine whether immune privilege parameters assayed in aqueous humor are relevant to the fate of penetrating keratoplasty in humans.

Methods

Anterior chamber puncture was performed in 28 patients prior to PK (prospective cohort, 67% normal risk KP), in 6 of these patients with no history of graft rejection undergoing cataract surgery after PK (acceptors, 65% normal risk KP), in another 6 patients undergoing treatment of an acute endothelial immune reaction (rejectors, 33% normal risk KP), and in 65 controls undergoing uncomplicated cataract extraction. All aqueous humor (AqH) samples were tested for total protein concentration, ability to suppress in vitro T-cell activation, and total TGF-β2 content.

Conclusions

Assays of immune privilege markers in AqH reveal that mean TGF-β2 content is abnormally low in patients coming to PK due to the high risk cases and that PK surgery results in a sustained loss of integrity of the blood-aqueous barrier. Although trends were evident, values of immune privilege markers determined pre- and post-PK failed to predict graft fate or extent of endothelial cell loss with statistical significance. Identification of further parameters predicting graft outcome is subject to forthcoming investigations.